&#34;quasi-absolute&#34; digital control system for winding filament on mandrel



June 3, 1969 E. K. BRAMBLETT n. ETAL 3,448,253

"QUASI-"ABSOLUTE" DIGITAL CONTROL SYSTEM FOR WINDING FILAMENT ON MANDRELFil ed Nov. 22. 1963 Sheet of 4 INVENTORS ERNEST K. BRAMBLETTII RICHARDW. CLAPP AGENT E. K. BRAMBLETT u. ETAL 3, 8, 53- "QUASI-ABSOLUTE"DIGITAL CONTROL SYSTEM FOR WINDING FILAMENT ON MANDREL Sheet 2 of 4 June3, 1969 Filed Nov. 22,1963

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INVENTORS ERNEST K. BRAMBLETTII RICHARD w. CLAPP AGENT June 3, 1969Filed Nov. 22, 1963 E. K. BRAMBLETT II, ETAL "QUASI-ABSOLUTE" DIGITALCONTROL SYSTEM FOR WINDING FILAMENT ON MANDREL Sheet 4 014 INCRE MENTORDO NOT CHANGE NUMBER IN HIGH ORDER REGISTER POSITION INCREMENTORINCREASE NUMBER IN HIGH ORDER REGISTER POSITION YES INCREMENTOR DECREASENUMBER HIGH ORDER REGISTER POSITION COMPARATOR IS THE SIGN THE SAME 72INCREMENTOR DO NOT CHANGE NUMBER IN HIGH ORDER REGISTER POSITION FROM86L.

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I I I I I I I I I l I I COMPARATOR I IS THE NEW l NUMBER LARGER THAN THEOLD NUMBER 5 INVENTORS ERNEST K. BRAMBLETTII RICHARD W. CLAPP AGENTUnited States Patent 3,448,253 QUASI-ABSOLUTE DIGITAL CONTROL SYSTEM FORWINDING FILAMENT 0N MANDREL Ernest K. Bramblett II, Canoga Park, andRichard W. Clapp, Tarzana, Calif., assignors to North American RockwellCorporation, a corporation of Delaware Filed Nov. 22, 1963, Ser. No.325,621 Int. Cl. G06f /46, 7/48 US. Cl. 235151.1 12 Claims ABSTRACT OFTHE DISCLOSURE This invention relates to a digital control system; andmore particularly to a system wherein an informationbearing, or programtape controls a machine having a movable feed-head.

Background For convenience, the present invention will be described interms of the movable feed-head being used for positioning the filamentduring a filament-winding operation (to be described subsequently); butthis particular usage is not to be construed as a limitation, since thefeed-head could alternatively hold a shaping or cutting tool, or asimilar device.

Filament-winding is a relatively recent innovation, and compriseswinding a continuous filament in a cocoon-like pattern to provide alow-weight high-strength shell.

For example, a continuous filament may be wound around the exteriorsurface of a cylindrical tank in such a manner that several layers ofthe filament cover each portion of the tank; the filament and the tankcombining their strengths to form a much-stronger composite structure.Alternatively, the filament may be wound around unusual-shapedstructures, like a nozzle of a rocket engine, to increase the strengthof the structure. Another usage of filament-winding is to wrap astructure of basic material that does not have a high strength; coverthe wrapping with an additional layer of the basic material; and addstill other alternate wrappings and layers of material to form a unitarystructure of high strength. Still another usage of filament-wrapping isto form a cocoon like wrapping around a mandrel, and to then remove themandrel to leave a Wrapped shell.

Generally, the filament is a continuous strand of highstrengthmate-rial, such as glass, that is coated with a suitable plastic. Whenthe cocoon-like wrapping is exposed to suitable curing conditions oftemperature, pressure, time, etc., the plastic coating of each strandcombines with the plastic coating of adjacent strands to form animpervious rfilament-andplastic structure, whose weightto-strength ratiois about one-third the ratio of a similar steel structure. This lowweight-to-strength ratio is particularly advantageous in rocket andsatellite projects; and is also useful in structures for tank trucks,pressure tanks, silos, oil storage tanks, chemical storage tanks, andsimilar structures.

An additional advantage of a filament-wrapped structure is that, shouldthe structure be punctured or slashed,

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it can be readily repaired by the use of a fiberglass-plasticimpregnatedpatch.

Filament-wound structures presently range up to forty feet in length,and fifteen feet in diameter. The large size of these filament-wrappedstructures introduces several problems.

First of all, the winding must be extremely accurate, because cumulativeerrors will place the final windings so far out of position that theoverall structure does not achieve the design strength expected from thewinding pattern. Secondly, presently-available coating-plastics tend tocure at room temperatures; and this tendency requires that thefilament-winding operations be completed as quickly as possible,preferably in a few hours; otherwise subsequent layers of the filamentwinding are not suitably bonded to the earlier layers. Therefore, thefilament-winding machine must be capable of high-speed operation.

Another problem arises in end-winding the [filament around the tops andbottoms of the tanks or mandrels. The curvature of the end-portionsrequires careful positioning of the filament; otherwise the filamenttends to slip off, or else fails to add the design strength to thestructure.

Still another problem results from the fact that the winding must betight; thus requiring a high, constant tension of the filament duringwinding.

A further problem arises for the fact that, ordinarily, thousands offeet of program tape would be required to control the movement of thefeed-head during the severalhour winding interval.

The above problems, and others, dictate that the filament-windingmachine have a feed-head that is capable of extremely-fast preciselongitudinal and in-out (radial) movements. In addition, the machinemust be massive enough to apply a constant fixed tension to thefilament. The machine is thus subjected to rapid acceleration anddeceleration of heavy masses; these rapid movements and the inertia ofthe moving parts complicating the precise positioning of the feed-head.

Objects and drawings It is therefore the principal object of theinvention to provide an improved filament-winding machine.

The attainment of this object and others will be realized from thefollowing specification, taken in conjunction with the drawings, ofwhich FIGUE 1 shows a pictorial view of a filament-winding operation;

FIGURE 2 shows a block diagram of the control circuitry;

FIGURE 3 shows the uniform feed-head movement produced by the equipment;

FIGURE 4 shows the effect of non-acceptable program information; and

FIGURE 5 shows a block diagram of a specific portion of the controlcircuitry.

Description of the invention The invention concept Will be understoodfrom FIG- URE 1. Here reference character 10 indicates a tank, mandrel,or other workpiece that is being filament-wound. One or more spools 12,containing plastic-coated glass filament, permit the filament 14 to befed over suitable guide rollers 16, and through a feed-head 18 mountedon a movable carriage 19, to be wound onto the rotating mandrel 10. Therotation of the mandrel draws the filament from the spool; certain ofthe rollers, such as 20, acting as tensioning devices to assure that thefilament is properly tensioned as it is wound onto the mandrel.

In a single-filament winding operation, only one spool of filament isused; whereas a multiple-filament winding operation draws filaments fromseveral spools, and juxtaposes the multiple filaments to form a ribbon.

The winding is performed as follows. As the mandrel rotates,interconnecting apparatus causes the feed-head positioning-carriage 19to move along a trackway 24 parallel to the longitudinal axis of themandrel. A precise positioning-rack 26, located adjacent to thetrackway, has its teeth engaged by precision gears mounted on carriage19; and suitable motors rotate the precision-gears to cause carriage 19to move to sequential longitudinal positions.

When necessary, other motors, mounted on carriage 19, cause feed-head 18to move radially, that is, toward or away-from the mandrel 10.

FIGURE 1 shows an end of the mandrel having, for illustrative purposes,two different types of windings.

Reference character 34 indicates a so-called helical winding, which isformed by rotating the mandrel and feeding the filament from alongitudinally-moving feedhead. The space between adjacent filaments,and the slant of the filament is a function of the rotational-rate ofthe mandrel and the movement of the filament-feed-head 18. The helicalwinding can thus be closely-spaced or widelyspaced, and may be slightlyor steeply slanted, by controlling the movement of the feed-head.

In order to form several overlapping layers of filament, the feed-headpasses back and forth along the length of the mandrel, each pass formingan additional layer of filament.

Reference character 40 indicates a polar type of winding. In order toform this type of winding, the mandrel is held substantially still,while the feed-head 18 moves longitudinally from one end of the mandrelto the other, to place a longitudinal Winding along a cylindricalelement of the mandrel. As the feed-head moves past the end of thecylindrical-portion of the mandrel, and reaches the hemi-sphericalportion of the mandrel, the rotation of the mandrel is accelerated, andthe feed-head moves radially inwardly to form the end-portion of thepolar winding. By the time that the feed-head has approached the centerof the hemispherical-like end of the mandrel, the mandrel has rotatedapproximately a quarter of a revolution; and the feed-head then backsout to form the rest of the end-portion of the polar Winding as themandrel rotates another quarter revolution.

When the single-wrap of the end-portion is completed, the mandrelrotation is stopped, and the feed-head again moves longitudinally to theother end of the mandrel, in order to form the polar winding along acylindrical section of the mandrel diametrically-opposite the first halfof the polar winding.

The end-winding process is repeated at the other end of the mandrel.

The total mandrel rotation for this complete polar-wrap is nearly, butnot exactly, a full revolution. Thus, the next polar winding is adjacentto the first; and upon continuation of this process, a completelywrapped structure is formed.

It may thus be seen that for this intricate type of winding, thefeed-head must race longitudinally the entire length of the mandrel,preferably at a rate of about five feet per second; must then stop itslongitudinal motion and perform a radial movement, at a rate of aboutone foot per second, toward the center of the mandrel; must then backout; and must then race longitudinally to the other end of themandrelwhereupon the end Winding is again formed.

Other winding-patterns require other types of feed-head movements. Itwill be understood that the high speed, tremendous acceleration anddeceleration of the heavy framework, and the precise positioningrequirements impose an unduly heavy burden upon the feed-headpositioning and control apparatus.

The filament-winding machine comprises several cooperating assemblies.One of these comprises apparatus for controlling the rotational speed ofthe mandrel, and for indicating the angular position of the mandrel atall times.

A second assembly comprises a tape-reader that reads the information onthe tape; and commands the movement of the feed-head in accordance withthis information.

A third assembly comprises apparatus for moving the feed-head in alongitudinal direction, and in a radial direction.

Other assemblies comprise arrangements for sensing the actual positionof the feed-head; for determining whether this is the desired position;and, if not, for re-positioning the feed-head to the desired position.

These assemblies are indicated in the block diagram of FIGURE 2. Herereference character indicates an arrangement for controlling themandrels rotational speed.

This arrangement comprises an adjustable mandrelspeed control 52, suchas a potentiometer, whose output may be amplified by a summing amplifier54, and then applied to a motor 58. The output of the motor is sensedand fed back, by means such as a tachometer feedback circuit 60, to thesumming amplifier 54. Thus, if the motorand therefore the mandrel-shouldhappen to accelerate undesirably, the feedback signal causes the summingamplifier 54 to slow the motor by means of a motor speed-control device56, which could mean closing a valve if the motor 58 is of the hydraulictype. Conversely if the motor should decelerate undesirably, thefeedback signal and the summing amplifier act to open the valve, so thatthe motor is accelerated to reach the desired speed set bymandrel-speed-control 52.

It may be desirable to have the mandrel rotate rapidly during theend-winding operation, and to have the mandrel rotate slowly during therest of the polar winding or during the entire helical winding. Theabove-described mandrel speed-control arrangement permits the mandrelspeed to be controlled by adjusting control 52 manually. Alternatively,the mandrel speed may be controlled by means such as a cam, whoseinstantaneous position is a function of longitudinal and/or radiallocation of the feed-head. In either case, the mandrel speed is thenmaintained by the above-described arrangement 50.

Reference character 62 indicates a device for detecting mandrelrotation, and thus indicating the instantaneous angular position of themandrel with respect to an initial starting position.

The mandrel-p0sition-indicating device 62, frequently called an encoder,is of the type that produces a pulse for each given amount of rotationof the mandrel. For example, after the filament-winding operation isinitiated, the mandrel-encoder 62 produces a pulse every time that themandrel rotates a given amount; say every time the mandrel rotatesone-thousandth of a revolution.

In actuality, each mandrel-encoder pulse comprises two or more pulsesthat have a given phase-relation; that is, one of them occurs before theother. If the mandrel were to rotate in the opposite direction, thedifferent phaserelation would indicate backward rotation. Thephaserelation and number of pulses is thus used to indicate the positionof the mandrel at all times.

These mandrel-encoder pulses are applied to a readout circuit 64 thatconverts the pulse into a form that may be used by subsequent circuitry.The converted pulses are then applied to a pulse-counting circuit 66that produces an activating pulse on the occurrence of e.g., everysixteenth mandrel-encoder pulse; the reason for this to be explainedlater.

As previously indicated, the desired movements of the feed-head havebeen carefully calculated, and the information has been recorded on aprogram tape 68 in the form of magnetism or punched holes. Forconvenience of explanation, the use of a punched-hole tape will beassumed.

In some cases the program tape 68 has information on as many as eightlongitudinal channels; and four transverse lines of information may benecessary to define the next location of the feed-head.

It is of course essential that the movement of the tape, and thelocation of the feed-head be closely and precisely correlated with therotation of the mandrel.

Rather than trying to maintain independent absolutelyprecise rates forboth the rotation of the mandrel and the longitudinal movements of thetape--which is diflicult, or programming both feed-head movement andmandrel-rotational on the tape-which requires prohibitively largeamounts of tape, the present invention uses the output of themandrel-encoder for advancing the tape, and thus commanding the movementof the feedhead to accomplish the desired winding pattern.

This is accomplished as follows:

The activating pulses from the pulse-counting circuit 66 are applied totape-reader 70, which uses the activating pulses to advance the tape.For example, if the mandrel has rotated sixteen-thousan'dth's of arevolution, the mandrel-encoder 62 has therefore produced sixteenpulses. The sixteenth pulse causes the pulse-counting circuit 66 toproduce an activating pulse, which is applied to the tape-reader 70;which thereupon advances the tape in order that the next-sequentialbatch of information there on can be read.

Thus, if the mandrel should be accelerated-intentionally orunintentionally-the activating-pulses are produced at a faster rate-sothat the programmed information on the tape is provided fast enough forthe speeding mandrel. If, on the other hand, the mandrel should bedecelerated, the activating pulses are produced at a slower rate, sothat the programmed information is not provided too fast. Thisarrangement assures that the tape is read at a rate corresponding withthe rotational rate of the mandrel; and obviates the difliculty and theprohibitively large amounts of tape associated with thepreviously-described approaches.

The tape reader 70 has several electrical outputs. One of these containsinformation related to the new desired longitudinal location of thefeed-head; and this output is applied to a longitudinal-locationreadout-circuit, 72, where the taped information is converted into asuitable electrical form; and is stored. Here it is checked for error byany of the well-known parity check-circuits 74.

The tape-reader 70 also has an output that contains information relatedto the new desired radial location of the feed-head; and this output isapplied to a radial-location readout circuit 76. Here it is convertedinto a suitable electrical form; and is stored. The radial-locationinformation stored here is also checked for error by paritycheck-circuit 74.

Simultaneously, a check is also made to assure that the tape hasactually advanced the required number of lines.

Should any of these checks indicate an error, a visual display (notshown) is produced.

A slight digression is necessary at this point.

The tape may be programmed in either of two ways. The first, andsimplest--known as the incremental method-programs the feed-head to movea given number of units (increments) from its last location.

For example, if the feed-head is to move from location 32 to location36, a tape programmed in the incremental manner would command a movementof +4 units (3632); the plus sign indicating movement in the forwarddirection. Similarly, if the feed-head is to move from location 32 tolocation 41, the tape would command a movement of +9 units (41-32). In asimilar manner, a feed-head movement from location 3-2 to location 28would require the program tape to command a feed-head movement of -4units, the negative sign indicating backward movement.

Unfortunately, if the circuitry were to make an error, and produce anincorrect movement, all of the subsequent feed-head locations would alsobe in error. Moreover, the errors are cumulative; and at the end of thewinding operation, the feed-head may be far from its desired location.

However, this incremental mode of programming handles only small numbers(+4, +9, -4); and thus requires a minimum amount of space on the programtape, and relatively simply circuitry.

The second way of programming the tape is known as the absolute method,and commands the feed-head to move to the absolute, or desired,feed-head location.

For example, if the feed-head is to move from location 32 to location36, a tape programmed in the absolute manner would command a movement tolocation 36. Similarly, if the feed-head is to move from location 32 tolocation 41-or to location 28-the program tape commands a movement tothe new location.

It will be noted that if the circuitry were to make an error, andproduce an incorrect location of the feed-head, the next command of atape programmed in the absolute manner would direct the feed-head to thenext correct location. Moreover, the errors are not cumulative.

It will be noted however, that the absolute mode of programming handleslarge numbers (36, 41, 28); that is, a representation of the entire newfeed-head-location must be stored on the tape. This requires a largeamount of space on the tape, and relatively complex large-numbercircuitry.

The absolute mode of operation requires that the equipment store eachnew desired location, subtract the last location of the feed-head fromthe new desired lo cation, and convert the difference into the necessaryfeed-head movement. While the absolute mode of programming is moredifficult to mechanize, it assures that the feed-head will be at thedesired location at all times.

A third factor must be considered. Since high threedecimal-placeprecision is required, and the mandrel may be forty feet long; afive-digit decimal location-number such as 39.000 may be required todefine the feed-head location in the absolute mode of operation.Alternatively a smaller four-digit decimal movement-number such as+4.000 may be sufficient to defiine the feed-hand movement in theincremental mode of operation.

As mandrels become progressively larger, the required absolute-modelocation-numbers become inconveniently large, and require such a largespace on the program tape as to make the program tape irnpracticablylong.

Still another factor must be taken into consideration. In view of therequired high-precision and smooth operation, the feed-head must undergoa large number of small movements. If all of these movements areprogrammed, in either the incremental or the absolute system, the tapeis again prohibitively long.

As will be seen later, the present invention solves these problems in anovel manner.

Continuing now with the explanation of the windingmachines operation, ifthe tape-advance check or any parity-check indicates an error, theerroneous feed-head information is ignored; and the subsequent feed-headinformation from the next programmed batch of information is used. Thisprevents the feed-head from being moved to an undesired location.Moreover, if the indicated feed-head information indicates an unusualtype or amount of movement, the indicated feed-head information is alsoignored in favor of the subsequent feedhead informationthe ignoringprocess and the use of the next batch of feed-head information to beexplained subsequently.

Thus, only acceptable feed-head information is stored in thelongitudinal and radial position readout-circuits, 72 and 76; and thisacceptance and storing operation takes place on the occurrance of everyactivating pulse.

Occurrence of the next (sec-0nd) activating pulse from pulse-countingcircuit 66 causes the tape to advance; and causes new feed-headinformation to be applied to location-readout circuits 72 and 76, whereit is checked and stored as described above.

For ease of explanation, the rest of the explanation will be in terms oflongitudinal feed-head location only; it being understood that radialinformation is processed in the same way.

In a manner that will be understood from the following explanation, theprevious desired longitudinal-location of the feed-head has been storedin the absolute longitudinal-location circuit 80L. Similarly, theprevious desired radial-location of the feed-head has been stored in theabsolute radial-location circuit 84R, the L and R indicating that thecircuitry is associated respectively with longitudinal or radialmovements of the feed-head. The longitudinal-and radial-locationcircuits 84L and 84R then are updated by appropriate circuitry tocontain the new desired longitudinaland radial-locations previously readfrom tape 68 into circuit 72.

In the occurrence of the next activating pulse, register control circuit84L subtracts the previous feed-head location-as stored in circuit84Lfrom the new desired feed-head location-as stored in circuit 72; thusobtaining the change in longitudinal feed-head location necessary toplace the feed-head in the new desired longitudinal location.

It will be recalled that in order to precisely indicate every locationof the feed-head for an interval of several hours, thousands of feet ofcontrol-tape would ordinarily be required.

Since it is impracticable to handle such large lengths of tape, thepresent invention programs the feed-head locations for only everyrevolution of the mandrel; and the equipment interpolates between thesebatches of information in the following manner. This procedure shortensthe program tape to the length otherwise necessary.

As thus far described, the change of feed-head location for each 7revolution of the mandrel is stored in register control circuit 80L bythe activating pulses that result from every sixteenth pulse from themandrel-encoder 62; the other intermediate mandrel-encoder pulses beingunused as thus far discussed.

In actuality, each of the pulses from the mandrelencoder 62 is used;each set of sixteen pulses dividing (interpolating) the desired-movementinto sixteen equal steps. This is done as follows.

Assume that the desired change in feed-head location, as commanded bythe tape 68, is stored in the register control circuit 80L; and happensto be sixteen units. Assume furtherfor ease of explanation onlythat theabsolute-location circuit 84L is empty, as might be the case at thestart of the winding-operation. This latter absolute-location circuit84L has a register 86L that registers the desired absolute location ofthe feed-head; the register containing a number of positions. The fourrightmost or low-order register-positions 86L are used forinterpolation, while the central or high-order registerpositions 86L"accept the overflow from the interpolation register-positions. Thus theabsolute-location register becomes filled with desired feed-headlocation-information. Register 86L also contains a sign position 86L.

By use of the well-known linear-interpolation technique, each of thesixteen pulses from the mandrel-encoder 62 transfers one-sixteenth ofthe desired position-change information (e.g., of the difference betweenthe old and the new absolute locations) from register control circuit80L to the lower order register positions 861.. in absolute-positioncircuit 84L, where the overflow of the newly-transferred information isadded to the information already there to provide the location desiredfor each revolution of the mandrel.

. FIGURE 3 is an illustration of the desired feed-head locations (storedin register 86L) as produced by the linear interpolation technique basedon mandrel rotation; the feed-head locations being plotted vertically,while the mandrel-encoder pulses are shown on the horizontal scale.Assume again that the desired change of feed-head location (totalvertical movement) is sixteen units. The staircase 71 of FIGURE 3 showsequi-spaced vertical interpolated locations of the feed-head, resultingfrom the sixteen sequential (horizontally-shown) mandrels-encoder ulses.

p It will be noted that each of the horizontally-shown mandrel-encoderpulses causes the feed-head to move upwards one unit (one-sixteenth ofthe sixteen-unit desired change). As shown, even if the mandrel-encoderpulses do not occur at regular intervals, as might happen if the mandrelrotation is erratic, the linear-interpolation technique, based onmandrel-encoder pulses, produces uniform one-unit feed-head locationchanges for each 0 revolution of the mandrel. Thus, without programmingthe feed-head location for each revolution of the mandrel, theinterpolation technique causes the location of the feed-head to changeone unit for each onethousandth revolution of the mandrel, regardless ofnonuniform mandrel rotation; and without the need for eitherregularly-timed pulses, constant-speed mandrel rotation, or program-tapecontrol of mandrel rotation.

In this way the program on the tape is reduced to onesixteenth; and thefeed head is still very previsely controlled to produce a plurality ofsmall, evenly-spaced movements.

Furthermore, the interpolation overflow into the highorder registerpositions 86L" of absolute-location circuit 84L causes circuit 84L to besimultaneously and continuously upgraded to indicate the instantaneousdesired feedhead location; and its contents may be checked against theprogrammed information every revolution of the mandrel, if desired, tofurther assure the accuracy of the operation.

Regressing for a moment, it was previously stated that if the paritycheck, or some other check indicated an unacceptable feed-head location,this unacceptable location-information was ignored; and the nextacceptable feed-head location was used. It may now be seen why this ispossible. If such erroneous information is ignored, the register controlcircuit 80L will not contain the sixteen-unit change in feed-headlocation between the first and second batches of information on thetape; but instead Will contain the thirty-two-unit change in feed-headlocation between the first and third batches of information.

The result is shown in FIGURE 4, where the solid-line staircase 73indicates the intended feed-head location change to be produced bylinear interpolation based on mandrel rotation. If however, the firstsixteen-unit change information is unacceptable because of a reason suchas an unsatisfactory parity check, no feed-head location change isindicated during the first sixteen mandrelencoder pulses; the absence offeed-head movement being indicated by the horizontal portion ofdotted-line 75. When the next acceptable programmed information isreceived, the subtraction circuit indicates a positionchange ofthirty-two units; and the linear-interpolation circuit produces sixteenequal position-changes for each of the next sixteen encoder pulses, asindicated by the dotted-line staircase portion of dotted-line 75.

As shown, even though one batch of information was unacceptable, thedesired absolute feed-head location is indicated after the thirty-secondmandrel-encoder pulse. Therefore, no cumulative errors are introduced.

It will be noted that during the first sixteen pulses of FIGURE 4 therewas no change of feed-head location, due to the fact that theinformation was not acceptable; and that for the second sixteen pulsesthe location-change of the feed-head was faster than programmed. As aresult, the movement of the feed-head, and the winding pattern duringthese thirty-two pulses is somewhat different than programmed; eventhough the feed-head eventuates at the desired location.

However, this discrepancy in winding pattern covers a mere of a mandrelrotation; an insignificant deviation that is preferable to an erroneouswinding pattern that would have been produced by using the unacceptableinformation; and is also preferable to stopping the winding processbecause unacceptable information was presented. Moreover, thepreviously-mentioned parity warning display calls attention to thepresence of unacceptable location information; and the reason for thiscan be investigated, and corrected.

Thus, the use of linear interpolation shortens the program tape bypermitting the programming of only onesixteenth of the feed-headlocations,

The present apparatus also uses another tape-shortening technique, asfollows. As previously indicated, the absolute-location circuit 84L ofFIGURE 2 contains register 86L, which contains a number ofregister-positions; and is thus able to store the desired feed-headlocation information in a manner to be described.

As previously indicated, the four right-most register position 86L areused for interpolation; the overflow from the interpolation positionsbeing added to the central high-order register-positions 86L; theleft-most register position 86L stores a sign bit.

It will be recalled that if the feed-head location is to change from+32.000 to +'36-.000, the absolute-position mode of programming wouldrequire sufficient space on the program tape to indicate the +32.000 andthe +36.000 values. These values would require sixteen positions forbinary-code storage. Thus, as previously indicated, the absolute mode ofprogramming would require impracticable lengths of tape.

The present invention uses a different concept. The desiredabsolute-location register 86L contains the old absolute location+32.000 in a binary form.

When the new feed-head position +36.000 is commanded, the actual tapeinput is a ,quasi-absolute +6.000, rather than a true absolute value of+36.000; that is, the new tape input is only a lower order portion ofthe new absolute location, such lower order portion having a maximummagnitude only suflicient to define the maximum location change for tapereading. Note that the tape input has a number of orders sufficient toencompass such change, but the digits of the tape input define not thechange, but a lower order portion of the new absolute location. Thelow-order register portion 86L has a size just sufficient to handle suchnew tape input, and the register control circuitry 80L subtracts the oldlocation (+2.000)--as stored in the register-postiton 86Lfrom the newquasi-absolute of input +6.000, to produce a location-change of -+4.000;the plus sign showing that the feed-head is to move forward 4.000 units,from location +32.000 to location +36.000. Attention is directed to thefact that this is in incremental technique.

Suitable location-change circuitry 85L of FIGURE 2, checks whether thenew location 6.000) stored in circuit 72 is greater than the +2.000currently in the loworder register position 86L; and whether the sign isthe same. In this case both conditions exist, so the locationchange(+4.000) is added--by the previously-described interpolation techniquetothe value +2.000, to produce a +6.000 in the low-order register-position86L; the number 3 in the high-order register position 86L, the +6.000 inthe low-order and sign register-positions 86L and 86 now representingthe new absolute feedhead location +36.000.

Thus, the modified-binary, absolute, and incremental techniques, plusthe use of interpolation, minimized the length of tape and registercapacity; while providing extremely precise feed-head location control.

If the feed-head has been programmed to go from position +32.000 to+41.000, the actual tape input would have been the quasi-absolute value+1..000, rather than the true absolute value +41.000; and the registercontrol circuitry 80L would have produced an increment +9.000 (+1000minus +2.000) for the desired change of feed-head location. This 9.000would be added by means of the interpolation technique to the 2.000 inthe low-order register-positions to 86L to produce a 1.000.Location-change circuit 85L checks whether the new location number(+1000) is greater than the +2.000 currently in the low orderregister-positions 86L, and checks the sign with that contained inregister position 86L. In this case the sign is the same indicating adesired movement in the forward direction; but the new location number(+1.000) is smaller than the old location number (2.000), indicatingthat the forward movement requires that the feed-head go from 32.000past the 39.000 feed-head location into the 40s. As a result, the 3 inthe high-order register-positions 86L is increased to 4; the inregister-position 86L the location number 4 in the high orderregister-positions 86L", and the 1.000 in the low-orderregister-positions 86L now representing the new feed-head absolutelocation +41.000.

If the feed-head had been programmed to go backward from position 32.000to +28.000, the actual tape input would have been the quasi-absolutevalue --8.000; and the register control circuitry L would have producedan incremental 4.000; which would have been added (subtracted) by theinterpolation technique, to the +2.000 in the low-orderregister-positions 86L to produce a new location number of +8.000 inregister-positions 86L to produce a new location number of +8.000 inregister-positions 86L. In this case the sign is different, indicating adesired movement in the backward direction; and the new location-number,+8000, is larger than the old number, +2.000; indicating that thebackward movement goes from +32.000 past the 30.000 feed-head locationinto the 20s. As a result, the 3 in the high-order register-positions86L is reduced to -a 2; the numbers 2 and 8.000 now representing the newfeed-head absolute location +28.000.

More-detailed location-change checking circuitry for controlling thechange in the high-order register-positions 86L is shown inblock-diagram form in FIGURE 5. As previously explained, this circuitrycompares the sign and the value of the quasi-absolute programmedinformation stored in circuit 72 with the information in theabsolutelocation circuitry 84L; and determines whether the numeral inthe high-order register position 86L" should be decreased, increased, orleft as it is.

It may thus be seen that the disclosed apparatus uses a quasi-absolute,incremental, interpolation concept to provide absolute location of thefeed-head; and that this concept permits shortening the program tape topracticable lengths, and also reduces the number of requiredregister-positions. Moreover, as the mandrels become increasinglylarger, the advantages of this concept over the pure absolute andincremental programming modes become even greater.

Referring again to FIGURE 2, in order to assure that the feed-head is inthe desired location, information is obtained from alongitudinal-feed-head location encoder L that is operated by thecarriage-moving arrange ment, and provides information about the actuallocation of the feed-head in the longitudinal direction. Encoder 100Lfeeds its information through a suitable readout circuit 102L into anactual longitudinal location circuit 104L.

A subtraction circuit 106L continuously compares the actual location ofthe feed-head-as indicated by actuallocation circuit 104L, with thedesired location of the feedhead-as indicated by register 86L inabsolute-location circuit 84L; and produces a feed-hand locationerror-signal that is fed to signal-utilizing means 108L that producesmovement of the feed-head. If the feed-head has already moved to thecommanded location, no error-signal exists, and the feed-head ispermitted to remain at this location.

If however, the feed-head is not actually at the commanded location, theerror-signal acts to increase or decrease the movement of the feed-head;so that the corrected movement brings the feed-head to the commandedlocation.

Advantages It will be realized that the disclosed apparatus has a largenumber of advantages. First of all, the quasi-absolute technique permitsa shortening of the program tape, and requires fewer register-positions.Secondly the use of the quasi-absolute technique obviates thepossibility of cumulative errors. Thirdly, only acceptable feed-headlocation is used; thus assuring that there will not be any gross errorsin the feed-head movement pattern. Fourthly, the interpolation techniquealso shortens the program tape; and provides a large number of smallfeed-head movements, without oven-loading either the tape or the tapereader. Fifthly, the use of the quasi-absolute incremental conceptpermits the use of smaller registers. Sixthly, the use of themandrel-encoder pulses obviates the need for precisely controlling themandrel rotation, programming mandrel rotation, or providingprecisely-timed clock-pulses. Seventhly, the absolute-location circuitryprovides the instantaneous absolute feed-head locations, which maytherefore be checked against the program tape, if so desired. Andfinally, the use of precisely-regulated feed-head movements, controlledby error signals, permits rapid feed-head movements with minimalpossibility of overshooting the desired location.

Although the invention has been illustrated and described in detail, itis to be clearly understood that the same is by way of illustration andexample only and is not to be taken by way of limitation, the spirit andscope of ths invention being limited only by the terms of the appendedclaims.

We claim:

1. In combination with a mandrel to be filamentwrapped, and a feed-headfor controlling the feed-point of said filament, the combinationcomprising:

means for positioning said feed-head to a location designated by anumber stored in a first register;

a second register adapted to receive quasi-absolute lower-orderfeed-head-location information from a tape; and

means for altering the lower orders of said number stored in said firstregister to correspond with said quasi-absolute lower-orderfeed-head-location information received from said tape.

2. The combination defined in claim 1 wherein said second register isadapted to accept only non-erroneous information from said tape.

3. The combination defined in claim 2 wherein said first and secondregisters each are adapted to store said feed-head location informationin a binary-coded format.

4. In a system having a mandrel to be filament-wrapped, a feed-head forcontrolling the feed-point of said filament, and means for positioningsaid feed-head to a location designated by the content of .a registerstoring feed-headlocation information in a binary-coded-location format,that improvement comprising:

means for ignoring non-acceptable feed-head-information from a tape, andfor accepting non-erroneous quasi-absolute lower-orderfeed-head-location information from said tape;

means for comparing the binary-coded-location information in saidregister with the non-erroneous quasiabsolute information from said tapeto produce valid feed-head-location change information; and

means for adding said valid feed-head location change information to thelower-order positions of said register in a linear-interpolation manner.

5. In combination with a mandrel to be filamentwrapped, means forrotating said mandrel, and a feedhead for controlling the feed-point ofsaid filament, the combination comprising:

means, comprising a mandrel-encoder, for producing pulses indicative ofthe rotational position of said mandrel;

means for positioning said feed-head, said means comprising a tapehaving quasi-absolute feed-head-location information thereon, saidinformation comprising a sign indicating the desired direction of motionof said feed-head and a lower-order portion of a number indicating a newdesired feed-head location; a tape reader; synchronizing means,responsive to said mandrel encoder means, for synchronizing saidtape-reader with said mandrel;

means, comprising a register for storing feed-head location informationin a binary-coded-location format, said register further adapted toreceive said quasiabsolute feed-head-location information from said tapereader;

means for ignoring unacceptable feed-head-information from saidtape-reader, and accepting subsequent acceptable feed-head-informationfrom said tapereader;

means for combining the information in said register with the acceptablequasi-absolute feed-head-location information from said tape reader,said means comprising means for adding, on the occurrence of every pulsefrom said mandrel-encoder, a portion of the feed-head change datagenerated from acceptable quasi-absolute information from saidtape-reader, thereby producing in said register the desiredinstantaneous location of said feed-head;

means for sensing the actual instantaneous location of said feed-head;

means for comparing the instantaneous desired actual location of saidfeed-head to produce an error signal; and

means for moving said feed-head in accordance wi said error signal.

6. In combination with a mandrel to be filamentwrapped, and a feed-headfor controlling the feed-point of said filament, the combinationcomprising:

means for positioning said feed-head, said means comprising a tapehaving quasi-absolute feed-head-location information thereon, saidinformation comprising a sign indicative of the desired direction offeedhead location change, and a lower-order portion of a number definingthe desired feed-head location;

a register adapted to contain a number indicating the desired locationof said feed-point;

means for altering the contents of said register in response toquasi-absolute feed-head-location information from said tape, said meanscomprising a signcomparator and a magnitude comparator, and means formodifying the number in the low-order register positions to correspondto the low-order information read from said tape.

7. A system for changing the absolute value of a number stored in .aregister, said system comprising:

means for storing a group of lower orders of a new absolute value ofsaid number and for storing the sense of the commanded change;

means for determining the sense of the difference between said new valueand the absolute value stored in said register;

means for changing the lower orders of said register to the lower ordersof said new value stored in said means for storing; and

means for controlling higher orders of said register in accordance withthe sense of said change and the sense of said difference.

8. The system of claim 7 wherein said means for changing the lowerorders includes interpolation means for effecting such change infractional increments thereof.

9. The system of claim 8 wherein said interpolation means comprises:

subtracting means for determining the magnitude of the differencebetween said lower orders of said new absolute value and the lowerorders of the absolute value stored in said register;

means for dividing said difference into a selected number of increments,and

means for adding each of said increments to the number stored in saidregister.

10. In combination with a storage register having storage orders forstoring a number N subject to repetitive change and that has apredetermined maximum value of L+C orders and a predetermined maximumvariation of C orders for each change, where L is of higher order thanmeans for introducing into said register a new absolute value of Ncomprising;

(1) quasi-absolute means for generating C orders of said new absolutevalues and the sense of the difference between such new value and theprevious stored value in said register;

(2) means for changing the C orders of said previously stored value tothe C orders of the new absolute value; and

(3) means responsive to said sense and to relative magnitudes of Corders of said new and said previously stored values for controlling thevalue of said L orders in said register.

11. In a filament winding machine having a mandrel to befilament-wrapped, the combination comprising:

(A) a source of filament to be wound on said mandrel;

(B) feed-head means for controlling the instantaneous feed-point of saidfilament from said source onto said mandrel;

(C) positioning means for positioning said feed-head from a locationdesignated by a given number to another location designated by a newnumber, said feed-head-positioning means comprising a tape means forstoring a group of lower orders of a new absolute value of the newnumber, said positioning means comprising;

(1) first means for storing the absolute value of said given givennumber;

(2) means for storing the sense of the commanded change and determiningthe sense of the difference between the lower orders of said new valueand the absolute value stored in said first means; (3) means forchanging the lower order of said first means to the lower orders of saidnew value; (4) means for controlling higher orders of said first meansin accordance with the sense of said change and the sense of saiddifference; and (5), means for moving the feed-head to the positionidentified by the number now in said first means.

12. In a filament-winding apparatus having a filament feed-headpositionable to a location defined by a number stored in a register,that improvement comprising:

means for accepting data comprising a sign indicative of the directionof desired feed-head location change and a lower-order portion of .a newlocation-defining number,

means for replacing the lower-order portion of the number stored in saidregister with said accepted lower-order, and

means for altering the higher-order portion of the number stored in saidregister in response to the sign of said data .and the comparedmagnitudes of the lowerorder portions of said stored number and saiddata.

References Cited UNITED STATES PATENTS 2,922,940 1/1960 Mergler 235-151X 2,964,252 12/ 1960 Rosenberg 242-9 3,062,995 11/1962 Raymond et a1.3,098,995 7/1963 Mundt 235151.11 X 3,148,316 9/ 1964 Herchenroeder.3,166,104 1/1965 Foley et a1. 242-9 X 3,172,026 3/1965 Schuman 235151.11X 3,246,125 4/1966 Morgler 235151.11 X

MARTIN P. HARTMAN, Primary Examiner.

I. KESCHNER, Assistant Examiner.

US. Cl. X.R.

